This invention relates to a method of lapping webs and the product resulting therefrom and, more particularly, to webs which thereafter can be further processed as by zig-zag folding or rewinding.
In the earlier above-identified applications, the solution of a 30 year problem of increasing the output of multi-fold machines by doubling the number of parent rolls to equal the single fold machines in production was achieved through the use of double three leaf multifold. More particularly, this was an improvement on the method of producing interfolded products where one or two parent rolls were employed and the folds introduced transversely of the unwound web and the resultant sheets dispensed in the stronger machine direction of the paper machine. This was in contrast to the other method of producing interfolded products where the webs were folded longitudinally (requiring 200+parent rolls for a 200 count package) and which were dispensed in the weaker cross machine direction.
In the earlier applications, webs from two parent rolls were separately cut to discrete sheets, each web having its own lapping system and thereafter the lapped sheets from the two individual parent rolls are brought together in a staggered reverse relationship whereby all of the exposed edges face one direction. The combined webs could then be zig-zag folded as in the convention system or, alternatively, rewound for sequential dispensing.
One possible draw-back of the invention using the double three leaf multi-fold was the fold-back of the leading edge of each sheet which could be objectionable in softer tissues.
One possible solution was to encourage the fold-back, as has been in the high speed bedroll for rewinders--as in U.S. Pat. No. Re. 28,353. Here it was not appealing, as the additional thickness of the folded edges would tend to produce a horseshoe shaped package, extremely difficult to package. Notwithstanding this apparent draw-back, the instant invention involved going beyond this point and, by adding another leaf or panel, transfers a full panel away from the leading, cut edge. Thus, it is possible to have 5 or more panels instead of 4, but from what has been seen so far 4 panels are optimal.
Contrary to the 3-leaf multi-fold, with the 4 leaf version, there is no need to break any bonds from a shear-cut severing of the sheet. For facial tissue, dispensed upward from a carton, small bonds (no the order of 0.012") should be a distinct advantage when higher counts in deeper cartons are used. However, if bonds are not desired in the final product, it is a simple matter to break the bonds before transfer.
According to the instant invention, webs from two parent rolls are weakened, i.e., either perforated or completely cut. Then no more than 1/4 of the leading edge portion--extending back from the line of weakness--is reversely folded--after which the web sections from each web are lapped and combined as in the 3-leaf multi-fold.